For packages hosted on pypy, you can install stash, then use the pip command

pip install pydicom

for pure python packages (which do not have C dependencies), this works maybe 75% of the time. in some cases, you may need to use pip download, then manually un tar or unzip the file, and copy the main package folder into site-packages.

For things on github, you can use git clone, from within stash. Or you can use wget with the github archive url, then un tar or unzip again with stash.